This is why we need better and honest religious education. Of course the Bible doesn't show that "god is evil" since there is no god.

What the "Old Testament" shows is that the god of the ancient Jews is a god of nature, to whom the ancient Jews ascribed the direction of the events of the world, both good and bad, as most cultures did.

When the ancient Jews were struck by plagues they believed that their god caused these as some form of punishment. When they were invaded and enslaved they believed that this was a form of punishment from their god, when there were famines, etc., etc.

As such, the ancient Jews believed in "collective punishment", because after all, these calamities typically happened to everyone, not just a few select people.

All that the "Old Testament" shows is that life is harsh, bad things happen all the time, and that ancient people believed that god or the gods were directing the events of the world, both good and bad.